Volume Measurements Comparison with Different Segmentation Methods Using VOCAL II System

The objective of this paper is to find out which is the best to calculate the volume of the sample using the virtual organ computer-aided analysis (VOCALtrade II) software. There are fifteen small eggs called "samples" assumed as breast tumors which real volumes are provided by the doctor of Huaxi hospital. The VOCALtrade II software provides three modes of sample\´s contour generation: Manual operation, automatic operation and semiautomatic operation. Sphere and Trace are two kinds of automatic operation. Hypo, cystic and hyperlso are three types of structures in semiautomatic operation. Each mode could choose four different rotation angles: 6deg 9deg 15deg 30deg , which defines the number of contour planes available. Moreover, the image rotated around the vertical axis is selected to be the reference image. The rotation angle of reference image is defined by the rotation step. Modes and rotation angles are combined to calculate the volume of the sample. Then compared with the fifteen real volumes, absolute measurement errors and relative measurement errors are calculated respectively. Manual operation is efficient; however, it is tedious and very time-consuming. Volumes measured by automatic operation are much bigger than real volumes. Semiautomatic operation has rather good performance and leads to a satisfactory result in comparison with the real volumes. The volume of the sample calculated by cystic-6deg operation is the best compared to real volumes. volume measured by different segmentation methods and parameters has different measurement error; also different measurement error could be got by different people using the same method even the same parameter. 3-D ultrasound can give more diagnosis information and will improve the diagnosis accurate rate.